Abstract: A method and device for longitudinally stretching polymeric film, characterized by the strict isolation of the tensioning operation from the heating and the cooling operations of the film, by the symmetrical heating and cooling of the film, and by carrying out the heating of the film in two stages, namely preheating by means of diffused IR-radiation, and a full heating, preferably along a line, by means of bundled IR-radiation. The film stretched in this manner meets high standards of flatness and surface quality, and is subject to minimum waste losses and is especially useful in the photographic field.

Abstract: A method of stretching a high molecular film by nipping the film through rubber-like resilient members and applying pressure thereto and an apparatus adapted to carry the method into practice, which apparatus is especially adapted to effect cold stretching of a high molecular film.

Abstract: The product of the present invention is a fabric woven from oriented polytetrafluoroethylene (PTFE) strands, in which the strands of the weave are interconnected by a multiplicity of fine PTFE fibrils. To produce this fabric, consisting entirely of PTFE, a woven PTFE fabric is heated substantially unrestrained to a temperature above the crystalline melt point of PTFE and stretched. Alternatively, a woven PTFE fabric may be impregnated with other fluorocarbon polymers, heated substantially unrestrained to a temperature above the crystalline melt point of PTFE, and subsequently stretched, thereby generating a multiplicity of fine fibrils interconnecting the weave.